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How to use sender reputation warming for better email deliverability

Reading Time: 5 minutes

You’ve just switched email marketing platforms, and you’ve set up all your mailing segments and you’re itching to send that first campaign to ALL of your subscribers.

But wait—have you warmed up your sender reputation?

Sender reputation warming is critical to having a strong email sender score, and maintaining great email deliverability. And neglecting this important step is a good way to damage your reputation.

I’m going to show you exactly how you can warm up your email sender reputation and get more ROI out of your email marketing efforts.

Let’s jump in:

What is an email sender reputation?

Your email sender reputation is the score given by Internet Service Providers (ISP), such as Outlook, Gmail, and Yahoo. The purpose of a sender reputation is to determine which senders should go to the inbox and which belong in the spam folder. To maximize your chances of landing in the inbox, it’s crucial to achieve a good sender score.

What is sender reputation warming?

Sender reputation warming is the process of gradually sending batches of emails in increasing increments.

This is an important step in establishing a good email sender score. New email accounts, including if you switch email marketing platforms, haven’t proven themselves to ISPs so if you immediately start to send a large volume of emails at once, you’re more likely to end up in a spam folder.

Start small and ideally send emails to recipients who are most likely to engage. This helps ISPs to recognize you as a legitimate sender, which improves your sender reputation. It’s also important to maintain the quality of your email list, as ISPs pay attention to this as part of their efforts to correctly identify spam.

If you’re switching email marketing platforms, it can take a little time for your email deliverability to reach your previous rate, but list cleaning and warming up your sender reputation properly will help to get you back there in no time.

Email deliverability is tricky—and sender reputation warming is a great way to make sure your emails will get to where they need to go.

Best tools to check your sender reputation

Sender Score

Sender Score

Sender Score exists to help you improve your IP reputation. It shows your current sender score, how your stats compare to the global email community, and if you’re included on the Return Path Blocklist. You can even upload your email list to verify the legitimacy of your subscribers. 

Barracuda Central

Barracuda Central

Barracuda is a technical website, aimed towards IT and system administrators, sharing statistics and threat information. It also has a variety of tools, including the helpful Barracuda Reputation System. Simply type your IP or domain and it will instantly tell you whether you’re on the Block List or not. If you are on it, you can take the appropriate steps to improve your domain reputation.



Mail exchange (MX) records direct email to a mail server, and MxToolbox lists a domain’s MX records in priority order. You can enter the domain name you want checked and instantly see DMARC Record check results, and it can tell you if you’re on any of the 100 DNS-based blacklists it scans. And if you do have deliverability problems, MxToolbox has tools to help you fix your domain reputation score.

Steps to improve sender reputation with Omnisend

Email warming generally happens over a period of weeks, but it can take a bit longer if receivers don’t perceive an explicit opt-in. The following process will build up your sender reputation and improve your email deliverability. You can also use email deliverability testing tools if you’d prefer.

If receivers don’t perceive an explicit opt-in, it might take a bit longer. This process will build up your sender reputation and your email deliverability will improve. Also, you can try email deliverability testing tools.

During the warm-up process, we recommend you send no more than 1 campaign per day, three times a week.

Warm-up sending volumes and segmentation recommendations:

Campaign 15,000Placed order once in the last 7 days
Campaign 27,000Placed order once in the last 14 days
Campaign 310,000Placed order once in the last 21 days
Campaign 413,000Placed order once in the last 30 days
Campaign 516,000Placed order once in the last 45 days

And so on. We even offer a full plan for paid users.

Here are some steps to help:

  • Transfer data from your previous marketing automation platform to Omnisend. When switching between platforms, you can retain the automation information you’ve collected on your customers from your previous email marketing platform, such as campaign engagement, opt-in date, order information etc.
  • Segment your contacts and start sending to those who are most engaged. If you can’t create segments in your previous marketing automation platform, download the data and import it to Omnisend with a particular tag.
  • Send according to the above warm-up plan. If there is no data from your previous platform, import your contacts bit by bit, starting with your most recent opt-ins. You want the most engaged recipients to receive your warm up campaigns.
  • During your warm-up, do not send more than 1 campaign per day, three times a week

If you notice that you’re not getting much engagement, don’t continue to the next batch. Send your next campaign to the same amount of subscribers again.

Graph explaining relation between volume of emails sent and sender reputation

If there are a lot of spam complaints, unsubscribes, or bounces in your campaign reports, check your subscriber list again. Are you sure they’re completely organic?

You have to follow good email practices otherwise your deliverability reputation can be permanently damaged and your account can be suspended. Shoot for a bounce rate under 3% and a 0.08% spam complaint rate.

Is sender reputation warming worth it?

The best part of sender reputation warming is that you can monitor and optimize your entire email list. If you use the segmentation recommendations, you’ll be able to find out who your most engaged segments are and adjust your campaigns around what they best respond to.

Building a great sender reputation is like building a foundation. You’ll find that your email marketing efforts will go a lot further if you take the time to build up your reputation. Instead of wondering where you’re going wrong and putting out fires, you can focus on fine tuning your email campaigns so that they’re the best they can possibly be.

During this sender reputation warming period, ISPs will evaluate how you send your campaigns, their content, and your subscriber engagement to see how well you maintain your list hygiene. They’ll be looking for how willing you are to send relevant information to responsive users.

It’s a perfect time to reassess your content, and pick out which emails are generating the most or least engagement.

Quality always wins out over quantity. Subscribers who don’t engage with your campaigns are the common cause of complaints, spam traps, and hard bounces. Too much of this means your email may find itself lower in an inbox, or an immediate banishment to the spam folder.

Wrap up

Creating amazing emails is only one component of email marketing—you also need to make sure they get seen!

If you don’t take the time to warm a new account, you could pay the price by having a bad sender reputation and landing in the spam folder. Not only will this mean you have low engagement on your campaigns, but you’ll also lose out on potential sales.

Another aspect of a good sender reputation is having a clean, healthy list that’s free from inactive subscribers. That’s why it’s important to regularly clean your list and only send to your engaged contacts.

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Richard White
Article by
Richard White

Richard is a Content Marketing Manager at Omnisend. An avid writer, he's said to have been born holding a pencil. Fascinated by all things handmade, if he's not reading or writing he can often be found practicing leathercraft.

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